Previously, it was reported that this season's Without a Trace and CSI would feature crossover episodes, with CSI executive Carol Mendelsohn telling TV Guide that the story will involve a serial killer. Mendelsohn also said the story had been in their “back pocket for a couple of years” and that the crossover episodes are the product of the relationship between actors Anthony LaPaglia and William Petersen, and producer/director Danny Cannon.

The crossover episodes will be kicking off November sweeps, but for those who want a sneak peek, continue reading for spoilers.

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According to CSI Files, The first half of the crossover begins with a CSI episode entitled “Who and What,” wherein Grissom (Petersen) and his team investigate a double murder. Things get more complicated for the CSIs when Jack Malone, LaPaglia's character on Without a Trace, shows up at the lab. Jack travels from New York to Las Vegas in search of a missing boy, and although he believes the dead child in Grissom's case is not the one he is looking for, he is sure the cases are connected.

To top it all off, the suspect in both cases is a serial killer.

The crossover continues on the eighth episode of Without a Trace, entitled “Where and Why.” According to Spoiler TV, the episode shows Jack and Vivian (Marianne Jean-Baptiste) in Las Vegas pursuing Terry Wicker, the serial killer and kidnapper who has taken his 10-year-old son. When the search moves back to New York, Jack and Vivian are joined by Danny (Enrique Murciano), Martin (Eric Close), Samantha (Poppy Montgomery) and Elena (Roselyn Sanchez) to find Wicker and save the life of his son.

The crossover episodes will reportedly air back to back on Thursday, November 1.

For those who do are unfamiliar with the shows, Without a Trace revolves around a missing persons unit of the FBI, with each episode following the team as they investigate the disappearance of a person and attend to issues of their own, while CSI follows a team of forensic scientists in Las Vegas. Both crime dramas air on CBS.